Just bought a 77 D-100 with a 440. The seller installed a new TM-7 intake and carb before I bought it. The problem I'm having is that after it warms up, it doesn't want to stay running. It keeps dropping cylinders until I bring the rpm's up. I noticed that he installed the aluminum intake using the stock valley pan intake gasket and nothing else. I'm thinking it should have had the Fel-Pro 1216 composite gaskets installed to sandwich the stock intake gasket. Wondering if that could be causing a nasty vacuum leak around the intake manifold?
Anyone ever encountered this?